A cave in South Dakota, untouched for possibly millennia, will be scoured for clues Monday in an effort to unravel the environmental history of the Black Hills.

The untouched gem, named Persistence and located in the Wind Cave National Park, has been shut off and kept secret for a decade, the Associated Press reported.

Researchers have no idea how big it is, but forceful gusts from its mouth implies unimaginable enormity. And there are few clues about where it goes, though it may be connected through an impassable passage to neighboring Wind Cave. If such a channel is clogged, that could explain why people exploring the latter over the past 100 years have never discovered it.

All these questions may soon be answered. Excavation teams have started work, removing sediment and bones to be analyzed, the Times Gazette added. Once they clear the entrance — which only fits two people at the moment — National Park Service staff and spelunkers will probe the untouched depths.

The bones may provide some interesting hints about the Black Hills’ past. So far, researchers have found the remains of animals that date to 11,000 years old. At least three of them have never been seen in the area before: pika, pine marten, and platygonus.

It’s the little pika that is giving scientists some tantalizing clues. The animal still lives in North America’s coldest, mountainous regions, and since it was found in this untouched cave in South Dakota, that means the region’s climate and environment were once pretty different than it is today.

Whatever the team of scientists digging their way inside find in the way of fossils, they’ll compare these to those found at another site called Mammoth Cave, from which researchers have already unearthed plenty of clues from prehistoric animal fossils, Tech Times reported.

Data from each will help paint a picture of how the area’s climate has changed, said Professor Jim Mead of Eastern Tennessee University, who’s leading the exploratory team.

For now, the location will keep its shroud of mystery while scientists study its interior. If Persistence and Wind caves are indeed connected, a walkway could be built in both to allow travelers to safely explore the wonders inside.

Until then, it’s one enormous scientific experiment.

“What we’re trying to do, centered through the Mammoth site, is to understand essentially the Ice Age environmental change through time. (It’s) just a warehouse of information. I’d be surprised if we don’t have at least 100,000 bones by the time we’re done this summer.”